Rb Head Vs Jz Head

[DennisRB30]

What flows better 1JZ and 2JZ heads VS RB25 and RB26 heads?

Has this been compared before? I head somewhere that a stock 1JZ head flows better than a RB26 head. Just wondering of this is true or not.

[NickR33]

1jz head was designed by Yamaha and in my limited knowledge flows better than the RB25 head... but I am sure someone who knows abit more will give you some more specific flow rates

[DennisRB30]

1jz head was designed by Yamaha and in my limited knowledge flows better than the RB25 head... but I am sure someone who knows abit more will give you some more specific flow rates

The 2JZ head is also desinged by Yamaha and flows better than a 1JZ by a fair margin. There was rumors going around that the 1JZ head was better but it has been proven to be bullshit.

http://www.supraforums.com/forum/showthread.php?t=339560

[Munna1]

I remember Sydneykid stating there is not much difference between a RB25 and RB26 head flow wise it the attachments that make the difference vavles etc.

Not sure if this helps but here is a comparison between a 1jz vs rb25 with the same turbo. The RB make a fair bit more power, and the curve does not drop off as much as the 1jz this may suggest that the RB flows better but im no expert on the matter.

HKS PRO-S comparison

cheers

[DennisRB30]

The 1JZ has very conservative cams which would explain the drop off in high RPM performance. Just wind the boost right up and the 1JZ will take it and out power the RB25. 1JZ747 runs mid 10's in a cressida with a stock 1JZ with stock cams but high boost. It makes an insane power level but at a shockingly low RPM. So the turbo comparison doesn't really prove much. Also your link does not seem to work?

Edited July 7, 2006 by DennisRB30

[psybic]

I remember someone on here posting the different flowing heads of jap engines.

EVO engine had the best flowing head, with the RB26 being one of the worst.. doesn't stop it from making a crap load of power. I'd say its probably true about the 1JZ.

[DoughBoy]

The 1JZ has very conservative cams which would explain the drop off in high RPM performance. Just wind the boost right up and the 1JZ will take it and out power the RB25. 1JZ747 runs mid 10's in a cressida with a stock 1JZ with stock cams but high boost. It makes an insane power level but at a shockingly low RPM. So the turbo comparison doesn't really prove much. Also your link does not seem to work?

... and there's a completely stock internal RB25 that did 10's in an R33 Skyline with a manual. All 4 of the engines are pretty damn good from the factory, especially given how cheap you can get the younger siblings (1JZ, RB25) for.

[DennisRB30]

... and there's a completely stock internal RB25 that did 10's in an R33 Skyline with a manual. All 4 of the engines are pretty damn good from the factory, especially given how cheap you can get the younger siblings (1JZ, RB25) for.

How many passes did it do before it blew up? tic

The 1JZ is without question the best value for money engine you can buy. Costs half as much as a RB25. At the time of purchase my 2JZ cost less than a RB25 from the same importer which is why I picked it.

Edited July 7, 2006 by DennisRB30

[DoughBoy]

Uh hang on, why did you post a question if you already know all the answers?

That '25 is still going, there's a big thread about it somewhere on SAU.

[DennisRB30]

Uh hang on, why did you post a question if you already know all the answers?

That '25 is still going, there's a big thread about it somewhere on SAU.

No I do not know anything about the actual twin cam RB head flows. Just that the JZ are better value for money IMO. I even posted a link to JZ headflows. But I don't know how this compares to actual tests on RBs. Saying some engine made more power does not prove much since there are too many variables. I was hoping someone tested them side by side.

Great to hear that 10sec RB25 is still going. Top work from the people involved. Got a link to the thread by any chance?

Edited July 7, 2006 by DennisRB30

[DoughBoy]

RB26 heads flow more std and have higher potential than 2JZ heads. I know it's a pretty bold statement, and the difference isn't that great (~10cfm) and I'm not going to post scans of flow sheets... you'll just have to trust me on this Oddly enough WRX heads flow better than either. I think the stronger bottom end of the 2JZ far outweighs the slight flow advantage the RB26 head has, unless you "invest" alot of moolah into it... which is probably insignificant if you are extracting over 300cfm from the heads.

[Guilt-Toy]

ive seen a 1jz running 14.5 af ratio's turn 406rwkw on 28 psi with stock engine. still running today.

All it had was a gt3540 82r with 38mm gate hks manifold exaust cooler 2j injectors and a safc.

He dont run it that high every day though lol

[DennisRB30]

So doughboy you have actually seen comparisons of the heads done by the same flowbench operator at the same lifts? I know the JZs have slightly smaller valves, and they seem to have very small exhaust ports but the intake sides look very good.

ive seen a 1jz running 14.5 af ratio's turn 406rwkw on 28 psi with stock engine. still running today.

All it had was a gt3540 82r with 38mm gate hks manifold exaust cooler 2j injectors and a safc.

He dont run it that high every day though lol

My brother and I are fitting 2 subaru turbos on his 1JZ and are going to run over 20psi with just a SAFC, 2JZ injectors, fuel pump and pressure reg. Should be interesting Gona make sure AFR's are in the 12's though

Edited July 8, 2006 by DennisRB30

[R31Nismoid]

So is this a general info thread?

A Nissan vs Toyota thread?

I dont see much point being this is a Nissan based forum, so who really cares what the 1j or 2j do?

[DennisRB30]

So is this a general info thread?

A Nissan vs Toyota thread?

I dont see much point being this is a Nissan based forum, so who really cares what the 1j or 2j do?

Info on RB head flows is related to skylines is it not? But yeah, I agree the thread did go a bit Nissan VS toyota.

[LBR33]

Keep in mind this is a skyline forum any view will be biased. Both are good engines they all have pros and cons, different mods are needed at equal power lvls and its hard to say that one is better then another it all depends on the project and available $$$$

[Sydneykid]

The problem with JZ's is the turbo is on the wrong side.

cheers

[The Dan]

The 2JZ head is also desinged by Yamaha and flows better than a 1JZ by a fair margin. There was rumors going around that the 1JZ head was better but it has been proven to be bullshit.

http://www.supraforums.com/forum/showthread.php?t=339560

I believe the 1J NA head flows more than the 2J Turbo head. They did this to make it less of a tank on the road.

[The Dan]

So is this a general info thread?

A Nissan vs Toyota thread?

I dont see much point being this is a Nissan based forum, so who really cares what the 1j or 2j do?

What if you had a 1J or 2J in your Skyline....I think I read correctly at the top where it says 'Skylines Australia' or is it just Skylines that have RB's fitted Australia?

Open your mind a bit.

[DennisRB30]

I do have a 2JZ in my skyline

If its true about NA's flowing more its mainly in the exhaust ports because they are kept small on the turbo engines to give awesome turbo response.

The turbo on the other side was not a problem for me, even though it was my first engine conversion and my first attempt at making an exhaust. If anyone is worried about this and its the reason they don't want to fit a JZ itno their skyline PM me about it.

JZ Skylines FTW

I would love a R33 or 34 4 door with a 2JZ. I might do it one day. IMO, Nissan make better cars Toyota make better engines. Give credit where its due I say I am allowed to think skylines are an awesome car and JZs are an awesome engine. Combine the two for the ultimate I say

Edited July 9, 2006 by DennisRB30